In accordance with the laws of thermodynamics, unprotected steel will always return to a state of low energy by corroding into iron oxide, its most relaxed, low energy form. In an effort to combat the deleterious effects of corrosion, automobile manufacturers have long shielded the steel body of an automobile with a protective, multilayered coating of paint. Unfortunately, during normal usage, cracks, scratches, dings, and other pores form in the protective coating of paint, resulting in the inevitable corrosion of the exposed, underlying steel.
Corrosion is a complex, continuous electrochemical process which occurs when the steel of an automobile is exposed to an electrolyte such as water. First, water comes in contact with the underlying steel, after passing through a scratch or the like in the protective coating of paint. Shortly thereafter, a solution comprising a small amount of dissolved iron is formed as the oxygen in the water combines with the iron in the steel, thus establishing a miniature electrochemical circuit ("corrosion cell"), wherein the imbalance of electrons between the solution and the surrounding steel creates a minute flow of electrons, or current. Unfortunately, as long as a current is allowed to flow, the steel will deteriorate, resulting in corrosion and pitting. Heretofore, automobile corrosion has been combatted using either a supplementary, protective chemical barrier, or a cathodic protection system. Unfortunately, as described in detail below, neither of these approaches have provided an effective and environmentally friendly, solution to the ever present, unstoppable forces of corrosion.
The most common method of preventing automotive corrosion requires the application of a supplementary dielectric chemical barrier, commonly designated as an "undercoating". Although such barriers do provide a certain degree of sound absorption and abrasion resistance, they do not effectively inhibit corrosion. More specifically, it is oftentimes very difficult, if not impossible, to apply a chemical barrier to all of the corrosion vulnerable areas of an automobile, even with the most sophisticated spraying equipment. Further, as known in the art, the application process typically violates the integrity of the automobile metal by requiring the drilling of a multitude of access holes therethrough, seals in moisture, and fouls window regulators, seat belt restrainers and other components of the automobile, potentially resulting in the nullification of the manufacturers warranty. Finally, regardless of the type of chemical barrier, surface electrolytes will eventually migrate through the barrier to the underlying metal of an automobile through transport phenomena such as osmosis, or through fissures in the chemical barrier, inexorably resulting in the formation of extensive corrosion beneath the protective chemical barrier. Regardless of the above-detailed disadvantages, the utilization of chemical corrosion barriers has drastically decreased over the last decade due in part to the environmental and health risks of the application process and the associated expenditures required to fully comply with the plethora of mandates set forth by the Environmental Protection Agency (EPA), the Occupational Health and Safety Administration (OSHA) and other governmental agencies. As a result, nonchemical substitutes, including cathodic protection systems, have been increasingly employed to combat corrosion.
Impressed current cathodic protection systems have long been utilized to effectively protect pipelines, bridges, ships and other metal objects against the destructive influences of corrosion. As known in the art, such cathodic protection systems are theoretically designed to inhibit corrosion by impressing a reverse current at each corrosion cell on the metal object. Generally, the impressed current is produced by coupling the output of a voltage source to the metallic object, or "cathode", which is to be afforded corrosion protection, through at least one resistive anode.
Recently, electronic cathodic protection systems have been developed to inhibit automobile corrosion. In a typical automotive application, the battery of the automobile is utilized as the source of power, and a plurality of anodes are distributed about the metal body of an automobile. Unfortunately, such systems, although providing a limited degree of corrosion protection in the general vicinity of each anode, have not been suitably designed to provide effective corrosion protection about the entire body of an automobile. Further, it has been established that the most significant area of corrosion is generally disposed at those points where the anodes are coupled to metal body (cathode) of the automobile. Although many attempts have been made to develop a corrosion resistant anode-cathode coupling, none of the currently available coupling systems effectively reduce corrosion at the anode-cathode coupling points on the automobile.